<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .login-container {
        position: fixed;
        left: 0;
        right: 0;
        top: 0;
        bottom: 0;
        background-image: linear-gradient(135deg, #575657, #078cf1)
    }

    .login__container--inner {
        width: 450px;
        height: 450px;
        border: 1px solid #ccc;
        position: absolute;
        right: 20%;
        top: 30%;
        background-color: hsla(0, 0%, 100%, .7);
        border-radius: 5%;
        box-shadow: 1px 1px 35px #fff;
        display: flex;
        justify-content: center;
        align-items: center;
        flex-direction: column;
    }

    .login__container--inner div {
        margin: 20px 0;
    }

    .login__container--inner input {
        height: 35px;
        border-radius: 5px;
        outline: none;
        border: 0;
        font-size: 20px;
    }

    .login__container--inner input:hover {
        border: 1px solid deeppink;
    }

    .login--inner__loginbtn {
        background-image: linear-gradient(160deg, #575657, 30%, #078cf1);
        min-width: 180px;
        border: none;
        outline: none;
        height: 35px;
        color: #fff;
        border-radius: 5px;
        margin-left: 45px;
        margin-top: 10px;
        cursor: pointer;
    }

    .login--inner__loginbtn:hover {
        border: 1px solid deeppink;
    }
</style>

<body>
<div class="login-container">
    <div class="login__container--inner">
        <div class="usn">
            <label for="username">
                用户名:
            </label>
            <input type="text" id="username">
        </div>
        <div class="psw">
            <label for="password">
                &nbsp;密&nbsp;码:&nbsp;
            </label>
            <input type="text" id="password">
        </div>
        <button class="login--inner__loginbtn">点击登入</button>
    </div>
</div>
</body>

</html>